An eerie calm descended on Gaza today as a 72-hour Egypt-brokered ceasefire between Israel and Hamas came into effect with the Jewish state withdrawing troops from the battered coastal strip, raising hopes of a lasting truce after a month of intense fighting.

Minutes before the ceasefire took hold at 8 a.M. (local time), Hamas fired a barrage of long-range rockets as revenge for Israel's "massacres", referring to the killing of nearly 1,900 Palestinians, mostly civilians.

Sirens went off in Ashdod, Ashkelon, Sdot HaNegev, Kiryat Malachi, Rehovot, Rishon Lezion, Gedera, Lod, Ramle, and in Ma'ale Adumim which is in east of Jerusalem. Six of the 17 rockets fired from Gaza were intercepted by the anti-missile Iron Dome defence system, the army said.

The Israeli forces responded with artillery fire, but the guns fell silent just before the truce came into effect.

The Israeli military said it has withdrawn its ground troops from Gaza for the humanitarian ceasefire in the conflict with Hamas.

Lieutenant Colonel Peter Lerner said troops would be "deployed in defensive positions" outside of Gaza and would retaliate to any violation of the truce.

Israel launched Operation Protective Edge on July 8 with the stated aim of ending rocket attacks and destroying tunnels used by Palestinian militants.

In a statement just ahead of the withdrawal, the Israel Defense Forces (IDF) said it had eliminated 32 tunnels designed to allow militants to carry out raids into Israel, destroyed 3,000 missiles on the ground and killed about 900 "terrorists".

The IDF estimated that some 3,300 rockets had been fired at Israel during this period, and that Hamas had another 3,000 rockets left for future use.

As many as 67 Israelis, all but three of them soldiers, have also died in the conflict.

As the fragile truce took effect, Intelligence Minister Yuval Steinitz said he was skeptical over its prospect.

"I am skeptical. Hamas has already violated six previous truce agreements, I hope that this time will be different but we have to wait and see," he told public radio.

The removal of Israeli troops from Gaza reduces the risk of renewed clashes, but the possibility of aerial bombardment remained on both sides.

The truce enables Gaza's 1.8 million residents to go out into the streets to pick up supplies and check on their abandoned homes. The conflict has displaced hundreds of thousands of people across the densely populated territory.

After the cease-fire began, residents trickled into Shujaya, an area near Gaza City that experienced some of the most destructive violence of the conflict.

They found craters and ruins where homes and shops once stood. People scaled crumbled concrete and twisted metal to rummage for any belongings left in the rubble.

Israel's Prime Minister Benjamin Netanyahu told his cabinet ministers late last night that he had agreed to a three-day ceasefire with Hamas starting this morning.

A spokesperson for Hamas, the Islamist faction that controls the Gaza Strip, simultaneously announced just after midnight that the militant factions had also decided to accept the initiative which stipulates that further discussions will take place in Cairo to try and reach a permanent agreement.

UN Secretary-General Ban Ki-moon issued a statement today calling for both parties to respect the terms of the truce.

Ban urged both sides to meet in Cairo and start talks for a long-term cease-fire agreement "as soon as possible."

It was not immediately clear as to when an Israeli delegation would head to Cairo for indirect talks on a long-term agreement.

Israel had refused to send a delegation on Sunday after the last attempt to broker a ceasefire broke down.

Political sources in Jerusalem yesterday said that Israel supports the Egyptian initiative.

"Israel wanted a ceasefire without preconditions and today the tunnel demolition was completed," they said, projecting that one of Israel's main concerns had been addressed.

The sources added that Israel would remain "prepared for the possibility that the ceasefire would be broken."

The Egyptian Foreign Ministry had announced the ceasefire initiative in a statement yesterday, saying "Out of concern for innocent lives and to prevent further bloodshed, Egypt calls on Israel and the Palestinian Authority and all the Palestinian factions to cease fire for a renewable period of 72 hours starting at 8 am".

Earlier, Azzam al-Ahmed, head of the Palestinian delegation to the Cairo talks on a ceasefire formula, confirmed that a truce would go into effect this morning.

Al-Ahmed, a senior leader of Hamas' rival faction, Fatah, said that the ceasefire would be for 72-hours during which Israel and the Palestinian factions would hold indirect talks in Cairo about consolidating the truce.

The Palestinian delegation had also presented a joint set of demands to the Egyptians late on Sunday calling for an immediate ceasefire and a lifting of the siege on the Gaza Strip, in addition to the reopening of all border crossings.

They sought international assurances that Israel would refrain from launching military attacks, and for UN assistance in rebuilding the Gaza Strip.